首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   113610篇
  免费   8635篇
  国内免费   441篇
耳鼻咽喉   1398篇
儿科学   2764篇
妇产科学   1850篇
基础医学   16189篇
口腔科学   2467篇
临床医学   11544篇
内科学   24128篇
皮肤病学   2093篇
神经病学   11986篇
特种医学   4953篇
外国民族医学   8篇
外科学   16224篇
综合类   1387篇
一般理论   77篇
预防医学   8577篇
眼科学   1810篇
药学   7743篇
中国医学   122篇
肿瘤学   7366篇
  2023年   566篇
  2022年   858篇
  2021年   2374篇
  2020年   1442篇
  2019年   2156篇
  2018年   2661篇
  2017年   1971篇
  2016年   2401篇
  2015年   2809篇
  2014年   3649篇
  2013年   4796篇
  2012年   7442篇
  2011年   7538篇
  2010年   4419篇
  2009年   4059篇
  2008年   6693篇
  2007年   7226篇
  2006年   6702篇
  2005年   6655篇
  2004年   6252篇
  2003年   5636篇
  2002年   5508篇
  2001年   2008篇
  2000年   1894篇
  1999年   1818篇
  1998年   1363篇
  1997年   1151篇
  1996年   928篇
  1995年   926篇
  1994年   794篇
  1993年   733篇
  1992年   1226篇
  1991年   1139篇
  1990年   1071篇
  1989年   1049篇
  1988年   912篇
  1987年   863篇
  1986年   891篇
  1985年   872篇
  1984年   731篇
  1983年   635篇
  1982年   623篇
  1981年   509篇
  1980年   452篇
  1979年   556篇
  1978年   441篇
  1977年   402篇
  1975年   367篇
  1974年   388篇
  1973年   370篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
International Journal of Clinical Oncology - Immune-checkpoint inhibitors (ICIs) are standard treatments for metastatic non-small cell lung cancer (NSCLC). Patients with poor performance status...  相似文献   
4.
5.
The current study explored the influence of three methods of parental emotion discourse (structured story-telling, reminiscing, and picture book) and their relation to preschoolers’ emotion understanding. Thirty-seven families participated in the study. Analyses showed that the structured story-telling method produced more emotion words, was high in unique emotion words, and was high for both emotion labelling and explanations. All three methods showed some potential to predict preschooler’s emotion understanding. Structured story-telling was best at predicting role-taking, while reminiscing and the picture book both were better at predicting situation knowledge. Additional studies are needed to further explore the influence of different methods of assessing emotion discourse to enhance validity and reliability of research in this field.  相似文献   
6.
7.
8.
9.
Nidogen 1 (NID1) is a glycoprotein found in basement membranes involved in cross-linking collagen IV and laminin. The role of NID in breast cancer has only been evaluated in a small number of studies and the findings of these studies have been inconsistent. Our previous work revealed that highly tumorigenic murine mammary tumor cells express high levels of Nid1 while weakly tumorigenic mammary tumor cells express low levels of Nid1. To investigate Nid1, two stable knockdown lines were created, and Nid1 knockdown was confirmed at both the mRNA and protein level. Nid1 knockdown significantly reduced cell proliferation and migration/invasion and these reductions in proliferation and migration/invasion could be rescued by conditioned media containing NID1 protein. The reduced migration/invasion observed in the Nid1 knockdown cells was not associated with significant alterations in the epithelial gene Cdh1 or the mesenchymal genes Snai1, Snai2, Twist1, Twist2, Zeb1 and Zeb2. Therefore, suppression of Nid1 expression reduces proliferation and migration/invasion in claudin-low murine mammary tumor cells.  相似文献   
10.
Prevalence of osteoporosis is more than 50% in older adults, yet current clinical methods for diagnosis that rely on areal bone mineral density (aBMD) fail to detect most individuals who have a fragility fracture. Bone fragility can manifest in different forms, and a “one-size-fits-all” approach to diagnosis and management of osteoporosis may not be suitable. High-resolution peripheral quantitative computed tomography (HR-pQCT) provides additive information by capturing information about volumetric density and microarchitecture, but interpretation is challenging because of the complex interactions between the numerous properties measured. In this study, we propose that there are common combinations of bone properties, referred to as phenotypes, that are predisposed to different levels of fracture risk. Using HR-pQCT data from a multinational cohort (n = 5873, 71% female) between 40 and 96 years of age, we employed fuzzy c-means clustering, an unsupervised machine-learning method, to identify phenotypes of bone microarchitecture. Three clusters were identified, and using partial correlation analysis of HR-pQCT parameters, we characterized the clusters as low density, low volume, and healthy bone phenotypes. Most males were associated with the healthy bone phenotype, whereas females were more often associated with the low volume or low density bone phenotypes. Each phenotype had a significantly different cumulative hazard of major osteoporotic fracture (MOF) and of any incident osteoporotic fracture (p < 0.05). After adjustment for covariates (cohort, sex, and age), the low density followed by the low volume phenotype had the highest association with MOF (hazard ratio = 2.96 and 2.35, respectively), and significant associations were maintained when additionally adjusted for femoral neck aBMD (hazard ratio = 1.69 and 1.90, respectively). Further, within each phenotype, different imaging biomarkers of fracture were identified. These findings suggest that osteoporotic fracture risk is associated with bone phenotypes that capture key features of bone deterioration that are not distinguishable by aBMD. © 2021 American Society for Bone and Mineral Research (ASBMR).  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号